1. Field of the Invention
This invention is for an improved sliding cover assembly for attachment to an open body truck for conversion to a closed body truck.
2. Description of the Prior Art
The advantages in having a sliding cover assembly capable of converting the open body of a truck to a closed body have long been recognized: on the one hand, the closed-body configuration can provide protection of cargo from adverse weather and from thieves, reduced wind resistance with improved fuel efficiency, and reduced risk of cargo being lost from the truck as by wind gusts; the open-body configuration, on the other hand, enables the truck to receive and transport large, bulky cargo that can not be loaded into the closed body of the truck.
In the prior art, such assemblies have generally included a pair of tracks mounted on the upper portions of the side walls of the open body of a truck, the tracks having lengthwise coextensive channels communicating with the interior space of the open body. Slidably mounted on the tracks was a cover means that could be slid forward to uncover the body and that could be slid rearward to completely cover the body. The assembly may also have included locking means for locking the cover means in the closed position, and possibly means for storing the cover means in the forward portion of the body, as by winding the cover means upon a drum.
Such an assembly was described by O. I. Groth, U.S. Pat. No. 2,992,040 (July 11, 1961; Class 296/100), who described an articulated-type cover means comprising a flexible covering sheet, rubberized fabric for example, and a plurality of transversely elongate, rigid members connected in parallel array to the undersurface of the covering sheet and extending across the body of the truck. Each member included a terminal head at each end in sliding engagement in a track. Although this could provide a watertight covering, the flexible covering sheet was easily susceptible to penetration as by a knife, and was, therefore, not theft-proof.
F. R. Cross described a slidable telescopic cover for the bed of pickup trucks and the like. U.S. Pat. No. 3,649,072 (Mar. 14, 1972; Class 296/137B). Cross's cover means comprised a plurality of transversely elongate, rectangular slat-forming panels wherein the trailing edge of each panel had a downturned flange and the leading edge of each panel included a downwardly and forwardly inclined cam surface terminating in an upturned flange thereby defining an unpwardly opening transverse trough. The downturned flange of each lead panel hooked behind the upturned flange of the adjacent following panel to define an interlocking chain thereof. In its fully-closed configuration, the panels lay in a substantially planar, close parallel array. The body of the truck could be uncovered by pushing forward on the trailing edge of the rearmost panel thereby causing the downturned flange on the panel second from the rear to begin to ride up on the inclined cam surface until it became tightly wedged between the latter surface and the upper rail of the track, whereupon, both the rear panel and the one second from the rear would start to move forward together. In this manner, one by one, the panels would be forced into stacked relation at the forward portion of the body of the truck. There were several problems with Cross's assembly, however: rainwater tended to leak through the cover means where adjacent panels interlock; there was excessive friction associated with the sliding of the ends of the panels in the tracks; if a track became deformed even slightly, forward sliding of the panels to uncover the body would tend to cause the panels rearward of the deformity to telescope into stacked relation instead of first sliding together to the front portion of the body; and the assembly in its closed configuration was not theft-proof as interlocked adjacent panels could be easily disengaged by pressing downward on the panels to create a gap between the leading edge of one panel and the interlocked trailing edge of an adjacent panel.
J. J. McKeon has described an assembly wherein the cover means was likewise comprised of a plurality of panels. U.S. Pat. No. 4,138,361 (Classes 296/98, 296/137D; Feb. 6, 1979). Each of the panels had a longitudinally-extending, generally hook-shaped flange depending from each of the longitudinal edges thereof, one of which was dimensionally smaller than the other, and wherein the smaller, hook-shaped flange of each panel was pivotably received within the larger hook-shaped flange of the adjacent panel. This permitted coiling and uncoiling of the cover means upon a drum in the forward portion of the body of the truck. McKeon's cover means suffered from some of the same disadvantages as Cross's: it tended to leak, the panels were easily disengaged one from another, and it lacked strength.
H. Z. Marvin described an assembly in which the cover means comprised a sheet of corrugated material extending between the tracks and across the open body, which cover means further comprised a plurality of wheels rotatably mounted along the left and right outer margins of the corrugated sheet and within the channels of the left and right tracks in order to reduce the friction of sliding movement of the cover means. U.S. Pat. No. 4,210,361 (Classes 296/210, 296/100, 296/219; July 1, 1980). The assembly included spring actuated return means mounted at a forward end of the open body and conected to the forward edge portion of the cover means. As an alternative embodiment for his invention, Marvin also described an articulated-type cover consisting of a parallel array of successively disposed panels, each panel having an arcuate edge portion somewhat cylindrical in shape with an opening along its full length for receiving a cylindrical member such as a shaft mounted at the other and adjacent edge portion of the panels. Each panel was bent at an obtuse angle near its shaft-shaped edge to permit the folding together of the panels one against the other as the cover is slid into the open body position. Strips of waterproof sheet material such as plastic were positioned over the junctures of the panels with their edges secured by clips on the panels in order to prevent leakage of rain, etc., between the panels. Marvin's corrugated sheet lacked strength and was not theft-proof. Likewise, his articulated-type cover had low strength and was vulnerable to thieves because the shaft portions of the panels could be popped out of the arcuate edge portions of the panels. Moreover, the method of waterproofing the panels was unsatisfactory because the waterproof sheet material could deteriorate and become dislodged.
J. T. Campbell described a sliding cover assembly for the bed of a pickup truck or the like characterized by a multichanneled track that permitted the user to close off all or a just a portion of the open body. U.S. Pat. No. 4,252,362 (Classes 296/98, 296/100; Feb. 24, 1981). Campbell described cover means including a double-layered fabric sheet and a plurality of transversely-extending rigid rods hemmed or otherwise secured in fixed spaced parallel relation between the double-layered fabric. Recognizing that this arrangement would not provide much security, Campbell suggested that the fabric part of the cover means should include some flexible wire mesh that both resists being cut and also inhibits its being pushed back along the rod. The ends of the rods inserted into the channels of the left and right tracks that were mounted on the side walls of the truck, each of the said ends having a nylon roller rotatably mounted thereon for rolling within the channels. Campbell's assembly, even if the cover means were reinforced with flexible wire mesh, was still vulnerable to a determined thief.
W. McMillan described a flexible cover assembly for vehicles including, in one embodiment, an articulated-type sliding cover. U.S. Pat. No. 1,950,927 (Class 296/1; Mar. 13, 1934). The cover comprised a parallel array of successively disposed panels formed from sheet metal, each panel having one end turned downwardly and rolled over upon itself to provide a hinge knuckle while the other end was left straight and was also turned over upon itself so as to form a hinge knuckle. The hinge knuckles of apposing edges of adjacent panels cooperated with each other to form hinged connections at the junctures of the panels, and a hinge pin was inserted through the knuckles at each juncture. The articulated cover was mounted for sliding movement in tracks. McMillan's assembly lacked the strength, compactness and low friction of my improved assembly.